In general, any metal in the near field of the array will have an effect on
pattern. This includes radials under the array. It's hard to predict what
the results will be in a particular situation, but it can be modeled in
EZNEC or other modeling programs. I've done this in the past and the
results for particular situations range from negligible effects to
significant pattern distortion. This is also true for any other receiving
array system. Such antennas are sensitive to metallic objects nearby, and
this needs to be taken into account in laying out an array.
My RX array is installed over the outer part of the radial field for my 160m
transmit vertical system. Modeling predicted little effect and in practice
I can't say I see any degradation in RX array performance. I also have a
switching arrangement that detunes the transmit vertical while I'm receiving
on the RX array. This arrangement is described in the user's manual.
73, John W1FV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Ron Feutz
Sent: Monday, December 07, 2015 10:58 PM
To: topband@contesting.com
Subject: Re: Topband: 9 circle array
The site I have available for one of these systems is part of the former
radial field for my now-defunct 160M 4-square. The RX array would go where
the ground has radials from the former elements. These radial wires are
buried under years of accumulated tree stuff and it would not be practical
to remove them. The radials are not physically connected to the radial
fields of the one or two transmit elements I will be using.
How would the old radial wires affect performance, if at all?
Ron KK9K
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|